Horizontal Wave Pressures on the Crown Wall of Rubble Mound Breakwater under Non-Breaking Condition

The crown wall with parapet on top of the rubble mound breakwater represents a relatively economic and efficient solution to reduce the wave overtopping discharge. However, the inclusion of parapet leads to increased wave pressure on the crown wall. The wave pressure on the crown wall is investigated by physical model test. To design the crown wall the wave loads should be available, and the horizontal wave pressure is still unclear. Regarding to the horizontal wave pressure on the crown wall, a series of experiments were conducted by changing the rubble mound type structure and the wave conditions. Based on these results, pressure modification factors of Goda’s (1974, 2010) formula have been suggested, which can be applicable for the practical design of the crown wall of the rubble-mound breakwater covered by tetrapods.

Experiments on Stability of Tetrapods on Rear Slope of Rubble Mound Structures under Wave Overtopping Condition

In this study, hydraulic model tests were performed to investigate the stability of armor units at harbor side slope for rubble mound structures. The Korean design standard for harbor and fishery port suggested the design figures that showed the ratio of the armor weight for each location of rubble mound structures and it could be known that the same weight ratio was needed to the sea side and harbor side (within 0.5H from the minimum design water level) slope of rubble mound structures. The super structures were commonly applied to the design process of rubble mound structures in Korea and the investigation of the effects of super structures would be needed. The stability number (Nod = 0.5) was applied (van der Meer, 1999) and it showed that the armor (tetrapod) weight ratio for harbor side slope of rubble mound structures needed 0.8 times of that for sea side slope.

THE INNOVATIVE BREAKWATER STRUCTURE

Most of the breakwater structures in various countries of the world are either gravitational or rock-fill types. The most optimal of them are gravity structures in the form of vertical walls. They are less material-capacious, are relatively quick prefabricated and reliably protect the port waters from storm waves. The construction of such structures began in the century before last many of them continue to fulfill their functional purpose. At first, ordinary concrete massifs were used for the construction of such structures, and then ferroconcrete massif-giants. The most ideal conditions for the construction of such structures are rocky soils. Nevertheless, in the world practice of marine hydraulically construction, there are cases of construction of berths and breakwaters of gravity type and on soft soils. Under such conditions, in later times, static loading of soil foundations was used under rubble-mound, as well as the beds themselves, by pre-installing concrete massifs at courses. Then, after stabilization of the subsidence, the masonry was dismantled, the planned-high-altitude position of the rubble-mound was finally corrected and the massifs were set along the courses to the design position, in sections. The duration of this technology took a rather long period of time, so its application in modern conditions seems impossible due to a significant increase in the construction time. In the last century, various technologies for artificial strengthening of soft soils were introduced into engineering practice. They require the use of specialized mechanisms, including those in the marine version. For this reason, the use of such technologies leads to a sharp rise in the cost of construction and an increase in its terms of building. Thus, the problem of build protective structures on soft soils exists at the present time. This problem was solved on the basis of an analysis of the technical condition of the constructed breakwater structures, as well as technologies for their construction in various climatic conditions and regions.